Natural killer cell IFN-γ-activity is associated with Plasmodium falciparum infection during pregnancy

The ability of natural killer (NK) cells to produce gamma interferon (IFN-γ) after ex vivo stimulation with crude schizont lysate of Plasmodium falciparum was studied in uninfected and P. falciparum-infected pregnant Gabonese women segregated according to the gravidity at the time of delivery. This activity was measured in purified NK cells as well as in whole blood from the periphery and cord. Crude schizont lysate-stimulated NK cells from primiparous women produced significantly more IFN-γ than those from multiparous women (P < 0.001). Women with malaria infection produced more IFN-γ than negative women in peripheral blood (P < 0.001) indicating that immunological determinants regulating the susceptibility to malaria in pregnant women are parasite-specific. These findings reveal that NK cells are major source of IFN-γ when exposed to P. falciparum antigens in vitro in absence of any other co-stimulant.